1. Field
This disclosure relates generally to semiconductor packages, and more specifically, to a semiconductor package providing reduced coupling between components included in a single semiconductor device package.
2. Related Art
Wireless communication systems often employ power amplifiers for increasing power of a signal. A power amplifier is usually designated as the last amplifier in a transmission chain (the output stage) and it is the amplifier stage that typically demands the most attention to power efficiency. In general, a power amplifier is designed to operate at maximum power efficiency when the power amplifier transmits peak output power. But power efficiency worsens as output power decreases, and modern communications standards typically employ signals operating at an average power that is lower than the amplifier's peak output power. In order to address power efficiency concerns, the Doherty power amplifier technique has been the focus of attention for both base stations and mobile terminals because of high power-added efficiency at all power levels.
A Doherty power amplifier typically includes two or more amplifiers (e.g., a “carrier amplifier” and a “peaking amplifier”). But a dual-path amplifier architecture, such as that for a Doherty amplifier, presents unique challenges in terms of semiconductor package design. The performance of a dual-path amplifier can be adversely perturbed, for example, by electromagnetic coupling (that is, the transfer of energy from one circuit component to another through a shared magnetic or electric field) between adjacent bond wire arrays of corresponding components of the amplifier. Coupling can be of two types, electric (i.e., capacitive coupling) and magnetic (i.e., inductive coupling). Inductive or magnetic coupling occurs when a varying magnetic field exists between current carrying conductors that are in close proximity to one another, thus inducing a voltage across the receiving conductor.
Space demands within typical wireless communication systems require the various components of those systems to consume minimal space. But placing both the carrier amplifier and peaking amplifier of a Doherty power amplifier in the same package results in the undesirable coupling discussed above. It is therefore desirable to provide a single semiconductor device package for a dual-path amplifier, such as a Doherty power amplifier, that reduces or eliminates the electromagnetic coupling between the elements of the amplifier.
The use of the same reference symbols in different drawings indicates identical items unless otherwise noted. The figures are not necessarily drawn to scale.